1. Field of the Invention
This invention relates to apparatus used to warn persons that an object has penetrated a perimeter sensor system. The improved warning system uses impact or pressure sensors to detect perimeter penetration and transmits this event to an alarm device located in the vicinity of or on the persons to be warned.
2. Description of Related Art
There are currently various methods and apparatus used to designate and protect areas in which roadway work personal are performing their tasks. These include the well known safety cone which is usually bright orange and may include reflective material. Lighting for night work is also incorporated in safety cones. Other apparatus include vehicles which have flashing arrow pointers to indicate a lane in the roadway is closed are also used. The traditional static signs warning of roadwork are commonly used. Even vehicles are placed in front of approaching traffic to act as safety barriers for errant vehicles to attempt to protect the workers.
More complex systems have also been proposed for use to warn roadway workers of moving vehicles which may pose a danger to them in their work environment. These concepts include those represented in U.S. Pat. Nos. 4,998,093, 5,265,556, 5,661,474 and 5,128,670. Additional disclosures and apparatus are also described in U.S. Pat. No. 4,998,093.
Most of the apparatus proposed for detecting vehicle movement in a sensor monitoring situation use a light beam detection system. Such systems essentially use a light source and a light detector to establish a detection system. If an object, such as a vehicle, interrupts the light beam path to the light detector an alarm activation mechanism is initiated to sound an alarm signal or otherwise give notice to persons that a vehicle has penetrated the designated area.
In U.S. Pat. No. 4,998,093 the alarm receiver is located with a person and includes an earphone so the individual will hear the alarm even in high ambient noise conditions such as on high traffic highways. For this alarm device the receiver normally receives a signal under no danger conditions and when the signal is interrupted when an object interrupts the light beam sensor an alarm is initiated. Also, if a system problem occurs to interrupt the signal to the receiver an alarm is sounded.
While many systems rely on optical light sensors to detect vehicles, some disclosures include the use of object motion detectors which are not defined in detail, but would involve some ranging technique such as a radar like unit. All of these systems, including the light beam sensor based systems, suffer from the problem of complexity in installation of the system at the work site. The systems must be properly installed to assure the integrity of the light path or motion detector field of view. For irregular road areas or unusual environmental conditions the sensors may be difficult or impossible to locate in the proper area.
An impact type device for traffic safety warning is disclosed in U.S. Pat. No. 5,265,556. However, the device is not a safety cone and is not compatible with safety cone use by road crews as is commonly done, i.e., it is not stackable, easily handled and the like use.
The present invention uses sensor elements which are much easier for the road workers to deploy to define the perimeter of the work area. The commonly used safety cone is fitted with an impact sensor and transmitter. This allows the user to use roadway warning safety cones in the normal manner to define the work area and notify drivers of the road work and its perimeter boundary. A pressure sensor tube may be used in combination with the safety cone or independently to provide warning of a vehicle penetration of the perimeter of the work area. These sensors have the advantage of ease of installation and reduced susceptibility to adverse environments as compared to light beam sensors and motion detectors which can be impacted by foul weather as an example.
While the use of a pressure sensitive air hose was disclosed in U.S. Pat. No. 4,998,093, it was discarded as being unworkable. U.S. Pat. No. 5,661,474 does disclose a hose sensor for pressure such as an automobile tire passing over the device. However, the invention does not allow storing all the elements on a reel, i.e., the junction boxes between hose lengths. This creates a cumbersome system. Contrary to this characterization, a properly constructed pressure tube or hose system can provide a work area perimeter sensor to detect vehicle intrusion. Again, these impact or pressure sensor elements combined with a means to transmit an event to an alarm element provide an improved system for ease of installation and use in rugged environments.